Carbohydrates - polysaccharides

Question 1

What is a polysaccharide and name three examples.

Answer 1

Many monosaccharides joined - Starch, glycogen and cellulose.

Question 2

Describe the structure of starch.

Answer 2

Starch is a mix of amylose and amylopectin,
Amylose is a long, unbranched chain of alpha-glucose. It has a coiled structure making it very compact.
Amylopectin is a long branched chain of alpha-glucose molecules, side branches caused by 1, 6, glycosidic bonds

Question 3

What is the function of starch?

Answer 3

Starch is the main energy store in plants.

Question 4

How is the structure of starch linked to its function?

Answer 4

Compact - fit lots in a cell.
Branches in amylopectin - allow easy access to enzymes to allow quick hydrolysis of glycosidic bonds to release energy.
Insoluble in water - does not affect water potential, meaning it does not cause water to enter cells by osmosis (would make cells swell) making it good for storage.

Question 5

Describe the biochemical test for starch.

Answer 5

Add iodine - blue/black= starch present